For what it's worth, calling for deplatforming people based on thinking they're racist based on what they wrote from when they were younger and uncharitable interpretations of a couple of tweets feels pretty "cancel-y" to me.

What were the clearly racist of bigoted things? 

Just for your information, as a non-binary person who was assigned female at birth (so definitely under-represented in EA), I would find it very upsetting if I knew you were trying to control which ideas and people I was exposed to. 

I find speciesist attitudes morally offputting, but if you would keep events from me because some people there were speciesist, I'd consider you to be being a bad friend. 

People are different. Some people consider what you're suggesting to be helpful. I do not. I just want you to be aware about the differences in preferences there, and not think that all "underrepresented groups" would feel uncomfortable going to events with speakers they deeply disagree with. 

I've actually read probably over 100 of his articles, and that's what's convinced me he's not racist. 

How much of his original content have you actually read? You can just check if you want. His writing is out there. 

I think most of people thinking he's racist have looked at one or two cherry-picked tweets and read articles written by other people about him and what he said, instead of looking at what he actually said. 

I don't know why he didn't delete it. I don't think it's particularly important to his main causes and points. If I were him, I'd totally delete it. 

My guess is that he feels pretty constantly attacked and he probably has a set of principles/rules he follows for when to delete stuff, and it's not "delete it if a lot of people are mad at me online", since people on the left and the right are often quite mad at him online.